A mixer having improved axial and radial mixing which retains good mixing time even during large viscosity changes, comprising a housing with at least one helical or anchor agitator located centrally in the housing in combination with at least one eccentrically arranged screw or blade agitator, preferably in mutual engagement, the combination of a helical agitator and a screw agitator enabling a much shorter mixing time as compared to a mixer having only a helical agitator without a screw agitator.